idiom · To hunger for or look upon something with intense envy and a strong desire to possess it.

他看着那块价值连城的宝石，露出了垂涎欲滴的神情。

idiom · To drool with desire, usually describing a strong physical reaction to the sight or smell of delicious food.

桌上色香味俱全的烤鸭令人垂涎欲滴。